SWIFT, a new method for MRI in dentistry

Objectives: A recently developed magnetic resonance imaging (MRI) technique, called SWeep Imaging with Fourier Transform (SWIFT), unlike other MRI technique, is able to visualize all dental tissues and is highly sensitive to pathology. The aim of this work is to explore the theoretical and practical aspects of SWIFT based dental MRI for clinical use. Methods: In-vivo SWIFT experiments were performed in a 90-cm, 4T-magnet interfaced to a Varian DirectDrive console. Radiofrequency (RF) transmission and signal reception were performed with custom fabricated coil with an intra-oral configuration. In-vivo imaging was performed on normal healthy volunteers determined to be exempt by the Institutional Review Board. Results: The jaw motion was greatly reduced by dedicated SWIFT-compatible coil holder and residual “rigid body” motions were subsequently compensated during image reconstruction. Pulse sequence and RF coil were optimized for exclusion and saturation of high intensity non-informative signals. Excitation sidebands were used for image reconstruction by oversampling during acquisition. Three-dimensional isotropic resolution of 300 microns was obtained from in-vivo teeth with total acquisition time less then 10 minutes. Conclusions: SWIFT MRI offers the direct and simultaneous visualization of densely mineralized tissues of enamel and dentin, as well as the soft tissues of in the pulp, within clinically relevant scanning times and without the use of ionizing radiation. Increasing image resolution and decreasing scanning time is possible with implementing parallel imaging strategies with future research. Supported from NIH Grants P41-RR008079, K12-RR023247, S10-RR023730 and the Keck Foundation.